Найдите значение выражения 1)0.8*(3а-14)-0.6*(6а-8) при а=- 3 1/12 2)6 1/9*(t-9)+2 5/9*(18- t) при t=0.2

1)0.8*(3а-14)-0.6*(6а-8) = 2,4а- 11,2- 3,6а+ 4,8 = -1,2а- 6,4= -(1,2а+6,4)

при а=- 3 1/12

- (1,2а+6,4)= -( 1,2• (-3 1/12)+ 6,4)= 12/10• (3•12+1)/12 -6,4= 12/10• 37/12 -6,4= 1/10• 37/1 -6,4= 37/10- 6,4= 3,7- 6,4= -2,7

2)6 1/9*(t-9)+2 5/9*(18- t)= (6•9+1)/9• (t-9)+ (9•2+5)/9• (18-t)= 55/9• (t-9)+ 23/9• (18-t)= 55/9•t- 55/9• 9+ 23/9• 18- 23/9•t= 55/9t- 55/1• 1+ 23/1• 2- 23/9t = 55/9t- 23/9t -55+ 46= 32/9t- 9=
3 5/9t -9

При t=0.2

3 5/9t -9= 32/9• 0,2 -9= 32/9• 2/10- 9= 32/9• 1/5- 9= 32/45- 9= 32/45- (9•45)/45= 32/45- 405/45= -(405-32)/45= - 373/45= -8 13/45